they have their own indepently driven clutches with jackshaft as apply the break on the left or right side it locks that side track up allowing for the oppiste side track to spin freely and it steeres toward that side that you lock up the track on, there will be a LH lever and a RH lever that controls that side of the machie for the breaks, then the levers u pull back pull up on that idler bully and engages that snowmobile bilt into the secondary clutch, then down to the drive axle, kinda same therory of how a dozer works